The UUID is unique to a partition and won't change if you would add a disk.
As an example, say you mount /home from sda4, then you add a disk as hd0 and /home becomes sdb4. With UUID in fstab you don't have to change fstab, with sda4 in there your /home won't get mounted before you change fstab.
Last edited by makuyl; 02-08-2009 at 05:17 PM.
Reason: Don't know what I was thinking before the edit.